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Some Aspects of the Eruption Mechanism of the Big Hole Maar, Central Oregon

1970; Geological Society of America; Volume: 81; Issue: 6 Linguagem: Inglês

10.1130/0016-7606(1970)81[1823

1943-2674

Volker Lorenz,

Seismology and Earthquake Studies

Research Article| June 01, 1970 Some Aspects of the Eruption Mechanism of the Big Hole Maar, Central Oregon VOLKER LORENZ VOLKER LORENZ Center for Volcanology, University of Oregon, Eugene, Oregon 97403 Search for other works by this author on: GSW Google Scholar Author and Article Information VOLKER LORENZ Center for Volcanology, University of Oregon, Eugene, Oregon 97403 Publisher: Geological Society of America Received: 14 Jan 1970 First Online: 02 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Copyright © 1970, The Geological Society of America, Inc. Copyright is not claimed on any material prepared by U.S. government employees within the scope of their employment. GSA Bulletin (1970) 81 (6): 1823–1830. https://doi.org/10.1130/0016-7606(1970)81[1823:SAOTEM]2.0.CO;2 Article history Received: 14 Jan 1970 First Online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Tools Icon Tools Get Permissions Search Site Citation VOLKER LORENZ; Some Aspects of the Eruption Mechanism of the Big Hole Maar, Central Oregon. GSA Bulletin 1970;; 81 (6): 1823–1830. doi: https://doi.org/10.1130/0016-7606(1970)81[1823:SAOTEM]2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract At the Big Hole maar in central Oregon, rising basalt magma came in contact with abundant ground water at a depth of more than 200 m below the surface, causing phreatomagmatic eruptions, possibly 20,000 yrs ago. Late-stage subsidence along a ring fault accounts for the large crater cut into older rocks. Subsequent erosion of pyroclastic debris in the crater wall increased the diameter of the crater while decreasing its depth.Investigation of the distribution pattern of large ejected blocks and application of a model of block acceleration in a dense rising two-phase system permits calculation of the apparent density and velocity of the fluid system. Values for the final strong eruptions are 0.01g/cm3 and 226 m/sec and for some of the earlier strong eruptions 0.01g/cm3 and 200 m/sec. The kinetic energy of some of the strongest eruptions was approximately 1.33 × 1021 ergs.Vesiculated tuffs, that is, tuffs with smooth-walled bubbles between the particles, are present between 1 and 2.5 km from the center of the crater; they appear to be the deposits of base surges. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.